Classic sculpture, sports photography, and dancers, oh my. I went for the most exaggerated poses I could find and tried to focus on rhythm over strict dimension. I think its enough to move on to adding skeletal landmarks.
Figure Drawing: Design and Invention by Michael Hampton
Remember that the figure is a machine in constant relationship with balance and imbalance — not just in the design of bones and muscle, but also of movement. Think of the natural activity of walking as an example. In order to walk, run — to move at all — we must throw ourselves out of balance, and with the next step catch it again. The reason all of our design elements are focused on asymmetry, balance, movement, etc. is essentially because we are describing a machine moving through a series of controlled falls.
Michael Hampton, Figure Drawing: Design and Invention